I just saw the movie 10,000 B.C. (No, not the movie about when ClearCase was created). Certainly a diversion from everyday tasks, but I found myself focused on a couple of aspects of the movie. My first reaction seeing the workers moving the stones to build the pyramids (never mind the accuracy, just stay with me) was: how long does it take to move a single stone up that ramp? What if it took the group of workers pulling it a whole day? And what happens if they pull it all the way to the top and it cracks? Or is the wrong size? Now you’ve got to get rid of the stone and you lost a day.
Now take a look at the developers around you. You’ve labored hard all day, you feel pretty good about your accomplishments, take a rest and review it tomorrow. But you come in the next day and the build failed. You hauled that code to right place, only to find it cracked and the wrong size. What have you got now? You lost a day, your workers are all pointing the finger at each other and management wants to know why there’s a delay. You’re now spending the second day figuring out what was wrong on the first day, delaying the work you should have done.
Sounds pretty bad right? What you need is a way to continuously check what is going on. So you ask each developer to run a build, maybe even run some tests before promoting their code. Each developer seems to be on track, but now those integration points keep burning you. Bob only thinks in Windows, he keeps making references that work on his machine. When Julie, your UNIX guru, gets them they never build. Now you need some integration checking. But if Bob performs the integration on Windows he doesn’t have a problem (today) and Julie is sick and tired of managing Bob’s work. The build guru you hired would mutiny if she had to run builds all the time. You need some automation to relieve the pain.
And along comes Continuous Integration (CI). Martin Fowler wrote a great summary of CI (you can find the materials here). Besides this article there are many tools and even some books that are worthwhile for in depth knowledge of CI (take a look at Continuous Integration: Improving Software Quality and Reducing Risk – a 2008 Jolt Award winner). I’ll do them all a disservice and sum it up: frequently integrate autonomously.
I find the keyword here is autonomously. I don’t understand why developers spend so much time writing software for others to improve their processes, and yet they are willing to manually and repetitively do their own work. And to top it off they will rewrite software over and over. Just as you shouldn’t be spending your time writing a file i/o subsystem for the umpteenth time, you shouldn’t be running your build processes manually for the umpteenth time. If you can spend 2% of your time integrating builds instead of 15% of your time, isn’t that better?
Some time ago we had the problem I described above with Bob and Julie. We had Windows developers whose code would prevent builds on occasion with another OS. We have six primary OS that we ship, with many other variants. You can imagine the pain when nearing a release date, if you were to come into the office and find out you have no build. Once this happens it becomes a midday manual process to run and test the build. What drudgery. CruiseControl can solve this problem, and with a little work, can run with your custom build scripts. CruiseControl can greatly reduce the loss of nightly builds, as a matter of fact I’m hard pressed to think of the last time a nightly build failed for this reason, although we’re looking into commercial offerings that provide even more value. For now, having developers speak up (Hey Joe, that checkin you just did failed on Linux) can reduce your own personal stress level. You’ll have less hesitation to check in code just before you go home, with less need for connecting the dots because CI has your back. On occasion driving home my phone still buzzes, and when it does I know the build failed. Not the nightly build, CI alerted us soon enough so I still have time to fix it before that.
No worries. We’ll get that pyramid done on time.
